Date   : Tue, 12 Sep 2006 21:47:37 +0100
From   : Sprow <info@...>
Subject: Re: Bugs in ArmCoPro OS

In article <000401c6d67f$7204ddb0$0301a8c0@...>,
   David Harper <dl.harper@...> wrote:
> Greg Cook wrote:

> > Try the DFS User Guide.  "On exit: A=0 implies operation attempted."
> > (The Advanced User Guide claims A is preserved.  I'm going with the
> > official doc.)
>
> On the other hand, the "official" Master Reference Manual (on page J.11-5) 
> states that A should be preserved.
>
> In practice, Acorn DFS and ADFS return with A=0 "if the operation was 
> attempted", but I am not sure how many other filing systems follow this 
> pattern.

Quite, it seems that A might be preserved if you're lucky, though it might
be corrupted too, or it might mean something about the implementation of the
call, or it might mean nothing. This renders it useless, inspecting C is
wiser.

By the SWI definition of OS_GBPB in PRM2 page 63 they've homed in on R0
being preserved,
Sprow.